1. Field of the Invention
The present invention relates to a controller or system for a hybrid vehicle which is provided with at least: a hybrid engine which includes an engine having an intake air volume regulating means for adjusting the volume of air to be taken into a combustion chamber and an electronically controlled fuel injector, a first rotary electric unit for determining the number of revolutions of the engine and a second rotary electric unit for determining the driving force of a vehicle, and a power converting means connected to the output shaft of the engine; and an electricity storing means.
2. Description of the Related Art
Hitherto, Japanese Unexamined Patent Publication No. 7-135701 has disclosed an apparatus which is equipped with an engine, a first motor, a second motor, and a gear unit composed of a first, second, and third rotary elements, which enables the engine to be operated at a maximum efficiency point by controlling the number of revolutions of one of the first motor and the second motor to determine the engine rpm and by controlling the torque of the other to determine the driving power of a vehicle, and which makes it possible to use the generated torque of the engine to be used directly as the driving power of the vehicle, thus permitting the generated energy of the engine to be transmitted with high efficiency.
Further, according to the specification of German Patent Application No. 4407666, a configuration has been disclosed; wherein the inner rotor of a first motor and the rotor of a second motor are directly coupled, the outer rotor of the first motor is driven by an engine, and the inner rotor and the outer rotor of the first motor are electromagnetically coupled to generate electricity thereby to electromagnetically transmit the output torque of the engine, and the power generating energy of the first motor can be used to enable the second motor to assist in torque, thus permitting highly efficient transmission of the generated energy of the engine. These hybrid vehicles are provided with a power transmitting means having two rotary electric units between the engine and the drive system thereby to make it possible to operate the engine at the maximum efficiency point and they are also adapted to transmit energy electrically and mechanically or electromagnetically at the same time to maintain high energy transmitting efficiency even if a traveling condition changes.
In the hybrid type vehicle disclosed in Japanese Unexamined Patent Publication No. 7-135701, the motor torque of one of the first motor and the second motor is controlled so that the engine reaches at a constant speed at the maximum efficiency point, and the torque of the other one of the first motor and the second motor is controlled according to the lift of an accelerator. Hence, excessive engine torque may occur, depending on the traveling condition of the hybrid type vehicle or the capacity of a battery, and if it occurs, then the engine is driven on an optimum efficiency line and the driving conditions is set according to the vehicle speed or the capacity of the battery. However, since the output of the engine is transmitted to a traveling load, the output required for travel may be generated by the engine. If the engine output is decided by the vehicle speed, then a problem arises in that an insufficient engine output results when climbing up a slope, while excess engine output results when traveling down a slope.
Further, in the control unit described above, only the configuration thereof has been disclosed in that an rpm command is issued to the first motor and a torque command is issued to the second motor in accordance with the lift of the accelerator and the engine rpm; the signals for engine control and the transmission of information are unclear. In the specification of the German Patent Application No. 4407666, only the configurations of the engine and the motors have been disclosed; the control of the engine and the motors has not been disclosed.
In the hybrid type vehicle described above, since the first motor is connected to the engine, the engine can be started up by the first motor. This is advantageous in that a starter motor for starting the engine can be omitted. There is, however, a disadvantage in that, when a predetermined torque is generated at the time of starting up the engine by the first motor, the first motor is rotated by the engine until combustion in the engine takes place and the startup process is completed; hence, the torque balance between the engine and the first motor is disturbed.
In such a case, the controlled torque of the first motor and the generated torque of the engine interfere with each other, and continued torque control will cause an excessive rise in the engine rpm by the torque of the first motor. This will consequently cause the engine rpm to overshoot at the completion of the startup, leading to uncomfortable startup. In addition, more electric energy than necessary will be drawn out of the electricity storing unit in order to generate the torque at the first motor, resulting in deteriorated energy efficiency. The problem can be controlled to a minimum if the complete explosion at the time of engine startup can be accurately detected and the engine can be properly controlled according to the startup state. In other words, a failure to accurately detect complete explosion will make the problem worse.